Production method of a molded article

ABSTRACT

A decorative sheet includes a base member made of a resin material and having a first and a second principal surfaces opposite to each other, a decoration layer provided on the first principal surface of the base member and having a pattern area representing a predetermined pattern, and a spread suppressing member provided in a position corresponding to the pattern area on the side of the first principal surface or on the side of the second principal surface of the base member, for suppressing the spread of the pattern area of the decoration layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a molded article, which is decorated,and a production method thereof. The present invention also relates to adecorative sheet used for decorating a molded article, and a motorvehicle provided with such a molded article.

2. Description of the Related Art

Recently, as a technique for decorating various kinds of moldedarticles, a technique for attaching a decorative sheet onto a surface ofa molded article has been proposed. The decorative sheet used in thistechnique is disclosed in Japanese Laid-Open Patent Publication No.10-249999, for example.

The decorative sheet disclosed in the above-identified publicationincludes a base member and an ink layer provided on a surface of thebase member by printing. The decorative sheet is attached to a moldedarticle with an adhesive. When such a decorative sheet is used, themolded article can be easily recycled as compared with the case of paintapplication using a coating material. In addition, such a decorativesheet creates a beautiful appearance which is different from paintapplication, such that the decorative quality is improved.

A conventional decorative sheet is, however, suitable for the decorationof a molded article having a flat surface, but is not suitable for thedecoration of a molded article having an uneven surface. When such adecorative sheet is attached to a molded article having an unevensurface, the decorative sheet is spread so as to follow the unevenness.Therefore, if a pattern of a character, a graphic symbol, a picture, orother decoration is represented in a portion of the decorative sheet,the pattern is deformed, and the decorative appearance is deteriorated.

SUMMARY OF THE INVENTION

To overcome the problems described above, preferred embodiments of thepresent invention provide a decorative sheet preferably used for thedecoration of a molded article having an uneven surface, a moldedarticle to which the decorative sheet is attached, a production methodthereof, and a motor vehicle provided with such a molded article.

A decorative sheet according to a preferred embodiment of the presentinvention includes a base member made of a resin material and havingfirst and second principal surfaces that are opposed to each other, adecoration layer provided on the first principal surface of the basemember and having a pattern area representing a predetermined pattern,and a spread suppressing member provided at a location corresponding tothe pattern area on the side of the first principal surface or on theside of the second principal surface of the base member, for suppressingthe spreading of the pattern area of the decoration layer.

In one preferred embodiment, the resin material is a thermoplastic resinmaterial.

In another preferred embodiment, the spread suppressing member has ahigher coefficient of thermal conductivity than a coefficient of thermalconductivity of the base member.

In another preferred embodiment, the spread suppressing member is madeof a material including metal or a metal compound.

In another preferred embodiment, the spread suppressing member is madeof metal.

In one preferred embodiment, a coefficient of thermal conductivity ofthe spread suppressing member is about 10 W/m·K or more.

Preferably, a thickness of the spread suppressing member is in the rangeof about 5 μm to about 100 μm.

Preferably, the spread suppressing member includes a first portion whichoverlaps the pattern area.

More preferably, the spread suppressing member includes a second portiondisposed in an outer circumference of the first portion.

Preferably, a width of the second portion of the spread suppressingmember is in the range of about 1 mm to about 10 mm.

More preferably, a width of the second portion of the spread suppressingmember is in the range of about 2 mm to about 8 mm.

The molded article according to another preferred embodiment of thepresent invention includes a molded article body and the decorativesheet having the above-described structure, which is joined to a surfaceof the molded article body.

In another preferred embodiment of the present invention, the moldedarticle includes a molded article body, and a sheet joined to a surfaceof the molded article body, wherein the sheet includes a base member anda decoration layer provided on a surface of the base member on the sideof the molded article body, the decoration layer has a pattern arearepresenting a predetermined pattern, and a portion of the sheetcorresponding to the pattern area has a thickness that is in the rangeof about 1.1 times to about 1.8 times a thickness of the other portionof the sheet.

Preferably, the portion of the sheet corresponding to the pattern areahas a thickness that is in the range of about 1.2 times to about 1.6times the thickness of the other portion of the sheet.

A motor vehicle according to another preferred embodiment of the presentinvention includes the molded article having the above-describedstructure.

A production method of a molded article according to another preferredembodiment of the present invention includes the steps of preparing adecorative sheet including a base member made of a resin material andhaving first and second principal surfaces that are opposed to eachother, a decoration layer provided on the first principal surface of thebase member and having a pattern area representing a predeterminedpattern, and a spread suppressing member provided at a locationcorresponding to the pattern area on the side of the first principalsurface or on the side of the second principal surface of the basemember for suppressing the spreading of the pattern area of thedecoration layer, preparing a molded article body, and joining thedecorative sheet to a surface of the molded article body.

In another preferred embodiment of the present invention, the productionmethod of a molded article includes, before the step of joining thedecorative sheet to the surface of the molded article body, the step ofheating the decorative sheet.

In another preferred embodiment, the resin material is a thermoplasticresin material.

In another preferred embodiment, the spread suppressing member has ahigher coefficient of thermal conductivity than a coefficient of thermalconductivity of the base member.

In another preferred embodiment, the spread suppressing member is madeof a material including metal or a metal compound.

In another preferred embodiment, the spread suppressing member is madeof metal.

In another preferred embodiment, the coefficient of thermal conductivityof the spread suppressing member is about 10 W/m·K or more.

Preferably, a thickness of the spread suppressing member is in the rangeof about 5 μm to about 100 μm.

Preferably, the spread suppressing member has a first portion whichoverlaps the pattern area.

More preferably, the spread suppressing member includes a second portiondisposed in an outer circumference of the first portion.

Preferably, a width of the second portion of the spread suppressingmember is in the range of about 1 mm to about 10 mm.

More preferably, a width of the second portion of the spread suppressingmember is in the range of about 2 mm to about 8 mm.

In another preferred embodiment, the step of joining the decorativesheet to the surface of the molded article body includes the step ofmoving the heated decorative sheet closer to the molded article body,and the step of reducing a pressure of a first space formed between thedecorative sheet that is closer to the molded article body and themolded article body as compared with a pressure of a second space thatis greater than the first space with respect to the decorative sheet.

In another preferred embodiment, the step of moving the decorative sheetcloser to the molded article body is performed such that the spreadsuppressing member faces the second space.

In another preferred embodiment, the production method of a moldedarticle according to the present invention includes, after the step ofmoving the decorative sheet closer to the molded body, the step ofcooling the spread suppressing member by introducing a gas into thesecond space.

In another preferred embodiment, the production method of a moldedarticle according to the present invention includes, after the step ofjoining the decorative sheet to the surface of the molded body, the stepof removing the spread suppressing member.

In another preferred embodiment, the spread suppressing member isprovided on the side of the second principal surface of the base member.

In another preferred embodiment, after the step of joining thedecorative sheet to the surface of the molded article body, thedecoration layer is disposed between the base member and the moldedarticle body.

In another preferred embodiment, the molded article body includes afirst member and a second member disposed on a surface of the firstmember, and in the step of joining the decorative sheet to the surfaceof the molded article body, the decorative sheet is joined to thesurface of the molded article body so as to cover both of the firstmember and the second member, thereby joining the first member and thesecond member.

The production method of a molded article according to another preferredembodiment of the present invention includes the steps of preparing adecorative sheet including a base member made of a resin material andhaving first and second principal surfaces opposed to each other, and adecoration layer provided on the first principal surface of the basemember and having a pattern area representing a predetermined pattern,preparing a molded article body, heating the decorative sheet, andjoining the decorative sheet, which has been heated, to a surface of themolded article body such that a temperature of a portion of thedecorative sheet corresponding to the pattern area is less than atemperature of the other portion of the decorative sheet.

In another preferred embodiment, the step of joining the decorativesheet to the surface of the molded article body includes the step ofcooling the decorative sheet such that the temperature of the portioncorresponding to the pattern area is rapidly reduced as compared withthe temperature of the other portion.

In another preferred embodiment, the decorative sheet further includes amember provided at a location corresponding to the pattern area on theside of the first principal surface or on the side of the secondprincipal surface of the base member and having a higher coefficient ofthermal conductivity than a coefficient of thermal conductivity of thebase member.

In another preferred embodiment, the member is made of a materialincluding metal.

In another preferred embodiment, the member is made of metal.

In another preferred embodiment, a coefficient of thermal conductivityof the member is about 10 W/m·K or more.

A motor vehicle according to another preferred embodiment of the presentinvention includes the molded article produced by the above-describedproduction method.

Other features, elements, steps, characteristics and advantages willbecome more apparent from the following detailed description ofpreferred embodiments of the present invention with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1( a) is a sectional view schematically showing a decorative sheetaccording to a preferred embodiment of the present invention, and FIG.1( b) is a top view schematically showing the decorative sheet accordingto a preferred embodiment of the present invention.

FIGS. 2( a) and (b) are views showing exemplary patterns represented bya pattern area of a decoration layer.

FIG. 3 is a sectional view schematically showing another preferredembodiment of a decorative sheet according to the present invention.

FIGS. 4( a), (b), and (c) are views schematically showing a preferredembodiment of the use of the decorative sheet according to the presentinvention.

FIG. 5 is a view schematically showing a preferred structure of a spreadsuppressing member.

FIGS. 6( a) and (b) are views schematically showing a preferredembodiment in which the decorative sheet according to the presentinvention is joined to a molded article body.

FIGS. 7( a) and (b) are views schematically showing another preferredembodiment in which the decorative sheet according to the presentinvention is joined to a molded article.

FIG. 8 is a sectional view schematically showing a producing apparatusused for producing a molded article with the decorative sheet accordingto a preferred embodiment of the present invention.

FIG. 9 is a process sectional view schematically showing a productionmethod of a molded article with the decorative sheet according to apreferred embodiment of the present invention.

FIG. 10 is a process sectional view schematically showing a productionmethod of a molded article with the decorative sheet according to apreferred embodiment of the present invention.

FIG. 11 is a process sectional view schematically showing a productionmethod of a molded article with the decorative sheet according to apreferred embodiment of the present invention.

FIG. 12 is a process sectional view schematically showing a productionmethod of a molded article with the decorative sheet according to apreferred embodiment of the present invention.

FIG. 13 is a process sectional view schematically showing a productionmethod of a molded article with the decorative sheet according to apreferred embodiment of the present invention.

FIG. 14 is a process sectional view schematically showing a productionmethod of a molded article with the decorative sheet according to apreferred embodiment of the present invention.

FIG. 15 is a time chart showing an exemplary time required for aproduction process.

FIG. 16 is a sectional view schematically showing a molded article.

FIG. 17 is a sectional view schematically showing a molded article.

FIGS. 18( a) and (b) are sectional views schematically showing acondition where a decorative sheet is joined to a molded article bodyhaving a plurality of members which are separately molded.

FIG. 19 is a view schematically showing a two-wheeled vehicle.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings. The presentinvention is not limited to the preferred embodiments described below.

A decorative sheet 10 in this preferred embodiment is schematicallyshown in FIGS. 1( a) and (b). The decorative sheet 10 includes, as shownin FIGS. 1( a) and (b), a base member 1 having a first principal surface1 a and a second principal surface 1 b which are opposed to each other,and a decoration layer 2 provided on the first principal surface 1 a ofthe base member 1.

The base member 1 is made of a resin material, and preferably of athermoplastic resin material. The decoration layer 2 is preferablyformed from ink. The decoration layer 2 includes a pattern area 2 arepresenting a predetermined pattern. The pattern represented by thepattern area 2 a is preferably a design such as a diagram, acolor-coding, or gradation, and more particularly, a character shown inFIG. 2( a), a graphic symbol shown in FIG. 2( b), or a picture.

In FIGS. 1( a) and (b), the decoration layer 2 having the pattern area 2a along an entire surface thereof is provided on a portion of theprincipal surface 1 a. Alternatively, as shown in FIG. 3, the decorationlayer 2 having the pattern area 2 a only in a portion may be provided onthe entire surface of the principal surface 1 a. An area 2 b other thanthe pattern area 2 a of the decoration layer 2 is, for example, amonotone area without any pattern.

FIGS. 4( a), (b), and (c) show examples of the use of the decorativesheet 10. The decorative sheet 10 is joined to the surface of a moldedarticle body 21, so as to decorate the molded article 20, as shown inFIGS. 4( a), (b), and (c). The decoration layer has a pattern area, suchthat improved decorating effects are achieved, as compared to adecoration layer having no pattern area (a monotone decoration layerwithout any pattern, for example). In other words, the pattern area isan area in which improved decoration accuracy is required as compared tothe other area of the decoration layer after being joined to the moldedarticle body 21.

The molded article body 21 shown in FIG. 4( a) has a protruding portion21 a of a substantially hemispherical shape (e.g., a bowl-like shape),and the surface is uneven. Therefore, when the decorative sheet 10 is tobe joined, the decorative sheet 10 is spread so as to follow theunevenness. In order to successfully perform the spread of thedecorative sheet 10, joining is preferably performed after thedecorative sheet 10 is heated and softened.

The decorative sheet 10 is provided with a spread suppressing member 3for suppressing the spread of the pattern area 2 a, as shown in FIGS. 1(a) and (b), and FIG. 3. The spread suppressing member 3 is provided at alocation corresponding to the pattern area 2 a. The spread suppressingmember 3 in this preferred embodiment is arranged so as to overlap thepattern area 2 a on the side of the second principal surface 1 b of thebase member 1 (on the side opposite to the side on which the decorationlayer 2 is provided).

The spread suppressing member 3 has a lower spreading property than thatof the base member 1, for example, such that the spread of the patternregion 2 a is suppressed.

Alternatively, the spread suppressing member 3 has a coefficient ofthermal conductivity that is greater than a coefficient of thermalconductivity of the base member 1, such that the spread of the patternarea 2 a is suppressed. If the coefficient of thermal conductivity ofthe spread suppressing member 3 is greater than the coefficient ofthermal conductivity of the base member 1, a temperature of a portion ofthe decorative sheet 10 on which the spread suppressing member 3 isprovided reduces more rapidly than the other portion after the heating.Thus, the spreading property is reduced as compared to the otherportion. Therefore, the spreading of the pattern area 2 a is suppressed.

The spread suppressing member 3 preferably has both of theabove-described physical properties, in order to effectively suppressthe spread of the pattern region 2 a.

If the joining as shown in FIGS. 4( a) to (c) is performed by using aconventional decorative sheet, the pattern such as a character, agraphic symbol, or a picture is deformed, such that the appearance ofthe molded article is deteriorated.

On the contrary, the decorative sheet 10 according to preferredembodiments of the present invention includes the spread suppressingmember 3, such that the spread of the pattern region 2 a in joining tothe molded article body 21 is suppressed. Therefore, when decoration ofthe molded article is performed using the decorative sheet 10 accordingto preferred embodiments of the present invention, the deformation ofthe pattern is prevented, and the appearance of the pattern is greatlyimproved. The spread suppressing member 3 is arranged so as to overlaponly a portion of the principal surface 1 b of the base member 1 inaccordance with the pattern area 2 a (that is, provided partially on theprincipal surface of the base member 1), such that the decorative sheet10 closely follows the unevenness of the surface of the molded articlebody 21.

Hereinafter, preferable materials, structures, and layouts of the spreadsuppressing member 3, the decoration layer 2, and the base member 1 willbe described.

As a material for the spread suppressing member 3, metal such asaluminum, copper, and stainless steel can be preferably used. As thespread suppressing member 3, a foil, a film, a thin plate, or othersuitable spread suppressing member made of any one of theabove-mentioned metals may be preferably used. Generally, a coefficientof thermal conductivity of metal is greater than a coefficient ofthermal conductivity of a resin by two or three digits. For this reason,if metal is used as the material for the spread suppressing member 3,the coefficient of thermal conductivity of the spread suppressing member3 is substantially greater than the coefficient of thermal conductivityof the base member 1 made of a resin material. Therefore, it is easy torapidly reduce the temperature of the portion of the decorative sheet 10in which the spread suppressing member 3 is provided. Thus, the spreadof the pattern area 2 a is effectively suppressed.

The spread suppressing member 3 is not limited to being made of metal.Since metal or a metal compound has a much higher coefficient of thermalconductivity than that of a resin, the coefficient of thermalconductivity of the spread suppressing member 3 will be sufficientlygreater than the coefficient of thermal conductivity of the base member1 by using a material including metal or a metal compound. As a materialincluding metal or a metal compound, for example, a material in whichfiller (inorganic filler) including metal or a metal compound is mixedin a resin matrix may be used. As a metal compound of the filler, forexample, a metal oxide such as alumina may be used.

In order to rapidly reduce the temperature of the portion of thedecorative sheet 10 in which the spread suppressing member 3 isprovided, and to effectively suppress the spread of the pattern region 2a, the coefficient of thermal conductivity of the spread suppressingmember 3 is preferably in the range of about 50 times to about 100 timesthat of the coefficient of thermal conductivity of the base member 1.Specifically, the coefficient of thermal conductivity of the spreadsuppressing member 3 is preferably about 10 W/m·K or more, and morepreferably about 15 W/m·K or more, and much more preferably about 20W/m·K. The coefficient of thermal conductivity of a resin material isabout 0.2 (the coefficient of thermal conductivity of polycarbonate is0.19 W/m·K, and the coefficient of thermal conductivity of acryl resinis 0.2 W/m·K, for example). On the contrary, the coefficient of thermalconductivity of alumina is about 21 W/m·K, and the coefficient ofthermal conductivity of aluminum is about 236 W/m·K.

Alternatively, as the material for the spread suppressing member 3, aresin material may be used. If a resin material having a higherdeflection temperature under load (a heat deflection temperature) thanthat of a resin material of the base member 1, or a resin materialhaving higher rigidity than that of a resin material of the base member1, is used, the spreading property of the spread suppressing member 3 isless than that of the base member 1, such that the spread of the patternregion 2 a is suppressed.

A thickness of the spread suppressing member 3 is preferably in therange of about 5 μm to about 100 μm. If the thickness is less than about5 μm, the strength is insufficient, and deformation or breakage mayoccur. If the thickness exceeds about 100 μm, in the case where metal isused as the material, the following property of the spread suppressingmember 3 with respect to the unevenness (convex and concave) of themolded article body 21 is insufficient. Thus, the spread suppressingmember 3 may peel off during joining.

As shown in FIG. 5, the spread suppressing member 3 preferably has aportion 3 a which overlaps the pattern area 2 a (an overlap portion).When the spread suppressing member 3 includes such an overlap portion 3a, the effect for suppressing the spread is directly achieved for thepattern area 2 a. Thus, the spreading of the pattern area 2 a iseffectively suppressed.

As shown in FIG. 5, when the spread suppressing member 3 also includes aportion 3 b which is disposed in an outer circumference of the overlapportion 3 a (an outer circumference portion), the spreading of thepattern area 2 a is more surely suppressed. From the point of view thatthe spreading of the pattern area 2 a is effectively suppressed, and thespreading of the portion other than the pattern area 2 a is notprevented, the width of the outer circumference portion 3 b of thespread suppressing member 3 is preferably in the range of about 1 mm toabout 10 mm, and more preferably in the range of about 2 mm to about 8mm.

Even if the spread suppressing member 3 does not include a portionoverlapping the pattern area 2 a, but has a frame-like shape along theedges of the pattern area 2 a, the spreading of the pattern area 2 a issuppressed. However, as shown in FIG. 5, when the spread suppressingmember 3 includes the portion 3 a overlapping the pattern area 2 a, thespread suppressing member 3 suppresses the spreading of the pattern area2 a more effectively.

As a material of the decoration layer 2, ink including a resin materialas a binder and pigment dispersed in the resin material can be used, asan example. The decoration layer 2 can be formed by printing with suchan ink, for example. The material of the decoration layer 2 ispreferably superior in heat resistance and flexibility. The inkdisclosed in Japanese Laid-Open Patent Publication No. 2002-275405 hassuperior heat resistance and flexibility, such that the ink ispreferably used as the material for the decoration layer 2.

As a resin material of the base member 1, a thermoplastic resin materialcan be suitably used, as described above. More specifically,polycarbonate (PC), acrylic resin, polyethylene terephthalate (PET),urethane resin, or other suitable resin material can be preferably used.However, since the base member 1 must have rigidity as a sheet basemember, it is preferred that a resin material be selected inconsideration of this rigidity. Although a thermosetting resin materialcan be used as the resin material of the base member 1, it is preferredthat a thermoplastic resin material be used in view of the formabilityof the decorative sheet 10.

A thickness of the base member 1 is preferably within the range of about100 μm to about 1000 μm or less. If the thickness of the base member 1is less than about 100 μm, it is difficult to handle the base member asa sheet, or there may occur a problem where the strength is notsufficient and breakage occurs in joining. If the thickness of the basemember 1 exceeds about 1000 μm, the following property with respect tothe surface of the molded article body 21 may be deteriorated.

The joining of the decorative sheet 10 may be performed, as shown inFIG. 6( a), such that the first principal surface 1 a on which thedecoration layer 2 is provided faces the molded article body 21, oralternatively as shown in FIG. 6( b), such that the second principalsurface 1 b on the opposite side to the first principal surface 1 afaces the molded article body 21.

The spread suppressing member 3 may be provided, as shown in FIGS. 6( a)and (b), on the side of the second principal surface 1 b of the basemember 1 (the side on which the decoration layer 2 is not provided), oralternatively provided, as shown in FIGS. 7( a) and (b), on the side ofthe first principal surface 1 a of the base member 1 (the side on whichthe decoration layer 2 is provided). In the case where the spreadsuppressing member 3 is provided on the side of the first principalsurface 1 a, after the decoration layer 2 is formed on the spreadsuppressing member 3 by printing or other processes, the accumulatedbody may be provided on the first principal surface 1 a of the basemember 1. Alternatively, the spread suppressing member 3 may be providedon both sides of the first principal surface 1 a and the secondprincipal surface 1 b of the base member 1.

As shown in FIG. 6( a) and FIG. 7( a), when joining is performed suchthat the first principal surface 1 a on which the decoration layer 2 isprovided faces the molded article body 21, the decoration layer 2 isarranged between the base member 1 and the molded article body 21 in thecompleted molded article, such that the decoration layer 2 isadvantageously protected by the base member 1.

On the other hand, as shown in FIG. 6( b) and FIG. 7( b), when joiningis performed such that the second principal surface 1 b faces the moldedarticle body 21, the decoration layer 2 is arranged on the outer sidethan the base member 1. Therefore, there is an advantage that inaddition to a transparent resin material or a translucent resinmaterial, an opaque resin material can be preferably used as the resinmaterial for the base member 1.

As shown in FIG. 6( a) and FIG. 7( b), when joining is performed suchthat the spread suppressing member 3 is arranged on the side opposite tothe molded article body 21 with respect to the base member 1, it ispossible to remove the spread suppressing member 3 after the joining.The appearance is prevented from being deteriorated because the spreadsuppressing member 3 remains in the completed molded article. Inaddition, the spread suppressing member 3 is not a portion of thedecoration in the completed molded article, such that the material forthe spread suppressing member 3 can be more freely selected (it isunnecessary to use a transparent or translucent material, for example).Thus, various materials such as metal can be used.

Especially when the spread suppressing member 3 is provided on the sideof the second principal surface 1 b of the base member 1 (on the sideopposite to the side on which the decoration layer 2 is provided), andthe joining is performed such that the first principal surface 1 a onwhich the decoration layer 2 is provided faces the molded article body21, as shown in FIG. 6( a), both of the advantages that the decorationlayer 2 is protected by the base member 1 and that it is possible toremove the spread suppressing member 3 are achieved.

For the fixing of the spread suppressing member 3 and the decorativesheet 10, an adhesive is preferably used, for example. As an adhesive, athermoplastic resin (thermoplastic polyurethane resin or thermoplasticacrylic resin) may be used, or a thermosetting resin (an epoxy resin,for example) may be used. When the decorative sheet 10 is heated beforejoining, the adhesive preferably has high heat resistance. Where thespread suppressing member 3 is removed after the joining, the adhesiveused for joining the spread suppressing member 3 is preferably easy topeel off. As an adhesive which has high heat resistance and which can beeasily peeled off, an adhesive of silicone type is preferable.

Next, a production method of a molded article using the decorative sheet10 and a production apparatus used in the production method will bedescribed.

First, a production apparatus 100 for the molded article is describedwith reference to FIG. 8. The production apparatus 100 includes, asshown in FIG. 8, a holding device (a holding frame) 30 for holding thedecorative sheet 10, a supporting device (a supporting table) 31 forsupporting the molded article body 21, a pressurizing box 32 arrangedabove the holding device 30 and the supporting device 31, a sealingcylinder 33 for moving the pressurizing box 32 up and down, apressurizing rubber hose 34 for introducing a gas into a space below thepressurizing box 32, a heater (a far infrared heater, for example) 35for heating the decorative sheet 10, and a vacuum vessel 36 foraccommodating the components of the production apparatus 100.

The vacuum vessel 36 includes a first vessel 36 a for accommodating theholding device 30, the supporting device 31, the box 32, the cylinder33, and the rubber hose 34, and a second vessel 36 b for accommodatingthe heater 35. The heater 35 may be introduced into the first vessel 36a via a door 37, if required.

The supporting device 31 has a plurality of openings 31 a. With a vacuumpump which is externally provided, the atmospheric air is sucked throughthe openings 31 a, thereby realizing a reduced pressure (evacuation) ofthe space spreading over the supporting device 31. The rubber hose 34 isconnected to the outside. By introducing a gas through the rubber hose34, the space spreading below the box 32 can be pressurized.

Next, with reference to FIGS. 9 to 15, a production method of a moldedarticle utilizing the decorative sheet 10 will be described. FIGS. 9 to14 are process sectional views schematically showing the productionmethod of the molded article. FIG. 15 is a time chart showing an exampleof periods of time required for respective steps.

First, the decorative sheet 10 such as shown in FIG. 1 is prepared. Thedecorative sheet 10 can be prepared from the above-described materialsby known techniques. For example, the decorative sheet 10 can beprepared in such a manner that a decoration layer 2 is formed byprinting with ink on a first principal surface 1 a of a base member 1,and a spread suppressing member 3 is fixed with an adhesive on the sideof a second principal surface 1 b of the base member 1.

In a separate step from the step of preparing the decorative sheet 10, amolded article body 21 is prepared. The molded article body 21 may beformed from a resin material, or may be formed from a metal material.Alternatively, the molded article body 21 may be formed from othermaterials, such as wood, for example. The molded article body 21 may betransparent, opaque, or translucent. The molded article body 21 ispreferably prepared by a known technique. Where a resin material isused, the molded article body 21 may be prepared by injection molding,for example. As the resin material, both of a thermoplastic resin and athermosetting resin can be used. Specifically, an unsaturated polyesterresin, an epoxy resin, a vinyl ester resin, a polyurethane resin, andother suitable resins may be used.

Next, as shown in FIG. 9, the molded article body 21 is placed on thesupporting device 31, and the decorative sheet 10 is fixed to theholding device 30 such that the decorative sheet 10 is arranged abovethe molded article body 21. At this time, an adhesive is applied to asurface of the decorative sheet 10 on the side of the molded articlebody 21. In this preferred embodiment, thereafter, the air in the vacuumvessel 36 is sucked through the openings 31 a of the supporting device31 by a vacuum pump which is externally provided. Thus, the pressure inthe inside of the vacuum vessel 36 is reduced. As the result of thepressure reduction, the internal pressure of the vacuum vessel 36 ispreferably about 2.7 kPa or less, for example.

Next, as shown in FIG. 10, the decorative sheet 10 is heated by theheater 35, thereby softening the decorative sheet 10. At this time, thedecorative sheet 10 is typically heated to temperatures equal to orgreater than a deflection temperature under load of the resin materialwhich forms the base member 1. If the heating temperature is too low, itis difficult to deform the resin material. Therefore, the resin materialmay be broken when being shaped (or attached), or the shaping itselfcannot be performed. If the heating temperature is too high, the sheettends to sag when heated, such that it is difficult to perform theshaping, or the appearance may be degraded because of air bubbles in theresin material. Therefore, it is preferred that the heating temperaturebe appropriately set in accordance with the type of resin material usedfor the base member 1. When polycarbonate is used as the resin materialfor the base member 1, the decorative sheet 10 is heated up to about195° C., for example. The movement of the heater 35 from the secondvessel 36 b to the first vessel 36 a is performed in about 3 to about 5seconds, for example. The heating by the heater 35 is performed forabout 15 to about 30 seconds, for example.

Thereafter, as shown in FIG. 11, the pressurizing box 32 and the holdingdevice 30 are moved downwardly by the cylinders 33, such that thedecorative sheet 10 is moved closer to the molded article body 21. Thedownward movement is performed in about 1 to about 2 seconds, forexample. In this preferred embodiment, the decorative sheet 10 is moveddownwardly. Alternatively, the supporting device 31 for supporting themolded article body 21 may be moved upwardly, such that the moldedarticle body 21 is moved closer to the decorative sheet 10.

Next, as shown in FIG. 12, a pressure of a first space formed betweenthe decorative sheet 10 and the molded article body 21 is reduced morethan a pressure of a second space expanded on the opposite side to thefirst space with respect to the decorative sheet 10 (that is, a spaceformed between the decorative sheet 10 and the pressurizing box 32). Asa result, the decorative sheet 10 is joined to the molded article body21, as shown in FIG. 13.

Specifically, together with the reduction of pressure in the first spaceby the vacuum pump, a gas is introduced into the box 32 through therubber hose 34, so as to pressurize the second space. As a result, thedecorative sheet 10 is pressed against the molded article body 21 with asubstantially uniform pressure, thereby joining the decorative sheet 10to the molded article body 21. The pressure is reduced in the firstspace such that the internal pressure of the first space is about 2.7kPa or less, for example. The pressurizing of the second space isperformed such that the internal pressure of the second space is about0.2 MPa to about 0.5 MPa. The reduced pressure condition of the firstspace and the pressurized condition of the second space are maintainedfor a predetermined period of time (for at least about 15 seconds, forexample). A temperature of the gas (the air, for example) introducedinto the second space is about room temperature (about 15° C. to about30° C.), for example.

Next, the vacuum vessel 36 is opened, such that the internal pressure ofthe vacuum vessel 36 is returned to be the atmospheric pressure.Unnecessary portions of the decorative sheet 10 are cut (trimmed) with acutting device, such as a rotary blade. Thereafter, the molded articlebody 21 is released from the supporting device 30, thereby completing amolded article 20, as shown in FIG. 14.

According to the above-described production method, the joining of thedecorative sheet 10 to the molded article body 21 is performed in a veryshort period of time (in about 1 second or less, as an example). Inaddition, during joining, the decorative sheet 10 is completely spread,but the spreading of the pattern portion 2 a of the decoration layer 2is suppressed by the spread suppressing member 3. Therefore, thedistortion of the pattern is prevented, and the appearance is notdeteriorated.

When the spreading property of the spread suppressing member 3 is lessthan the spreading property of the base member 1, the spreading of thepattern portion 2 a is suppressed. When the coefficient of thermalconductivity of the spread suppressing member 3 is greater than thecoefficient of thermal conductivity of the base member 1, thetemperature of the portion of the decorative sheet 10 in which thespread suppressing member 3 is provided (that is, the portioncorresponding to the pattern area 2 a) more rapidly decreases than thetemperature of the other portions of the decorative sheet 10. Therefore,the joining of the decorative sheet 10 is performed in a condition inwhich the temperature of the portion of the decorative sheet 10corresponding to the pattern area 2 a is less than the temperature ofthe other portions of the decorative sheet 10. Therefore, the spreadingof the pattern portion 2 a is further suppressed.

When the heating by the heater 35 is stopped, the decorative sheet 10 isallowed to naturally cool. As a result, the above-described non-uniformtemperature distribution of the decorative sheet 10 is achieved.Alternatively, positive cooling may be performed. When the gas isintroduced into the second space during joining, as in this preferredembodiment, the introduced gas can not only pressurize the second space,but also cool the surface of the decorative sheet 10 on the side of thesecond space. Therefore, when the spread suppressing member 3 faces thesecond space, the spread suppressing member 3 is cooled by the gas, suchthat the above-described non-uniform temperature distribution is rapidlyachieved. Therefore, even where the joining is performed in a very shorttime as described above, the spreading of the pattern area 2 a is moreeffectively suppressed.

Where the joining is performed such that the spread suppressing member 3faces the second space, the spread suppressing member 3 may be removedfrom the molded article 20, if necessary. If the fixing of the spreadsuppressing member 3 is performed using an adhesive that can be easilypeeled off, the removal can be easily performed.

The spread suppressing member 3 is not required to be in direct contactwith the first principal surface 1 a or the second principal surface 1 bof the base member 1. An adhesive layer is typically provided betweenthe base member 1 and the spread suppressing member 3, and additionally,another layer may be interposed. FIG. 16 is a partially enlarged view ofan example of the sectional structure after the joining.

In the structure shown in FIG. 16, on the second principal surface 1 bof the base member 1 of polycarbonate, a protecting layer 8 preferablymade of an acrylic resin is provided. On the protecting layer 8, thespread suppressing member 3 preferably made of aluminum is provided withthe adhesive layer 9 interposed therebetween. The protecting layer 8 isarranged on the outer side of the base member 1 in the molded article20, such that the protecting layer 8 protects the base member 1 andimproves the weather resistance of the decorative sheet 10. The basemember 1 has a thickness of about 200 μm to about 1000 μm, for example.The protecting layer 8 has a thickness of about 5 μm to about 50 μm, forexample. The spread suppressing member 3 has a thickness of about 5 μmto about 100 μm, for example. The adhesive layer 9 has a thickness ofabout 5 μm to about 50 μm, for example.

As shown in FIG. 16, on the first principal surface 1 a of the basemember 1, the decoration layer 2 preferably made of ink is provided. Onthe decoration layer 2, a metal layer 6 preferably made of tin isprovided with the adhesive layer 7 interposed therebetween. Since themetal layer 6 has metallic luster, the decorative sheet 10 has metallictones (metallic color) having a metallic appearance. Herein, the metallayer 6 is formed such that tin is evaporated on a carrier film 5, andthe layered body is attached to the first principal surface 1 a with anadhesive. The decoration layer 2 has a thickness of about 5 μm to about50 μm, for example. The metal layer 6 has a thickness of about 0.25 μmto about 0.8 μm, for example, and is preferably made of soft metal suchas tin.

The decorative sheet 10 shown in FIG. 16 is joined to the molded articlebody 21 by the adhesive layer 4. The adhesive layer 4 has a thickness ofabout 5 μm to about 50 μm, for example. As described above, the spreadsuppressing member 3 may be provided on the side of the first principalsurface 1 a of the base member 1. More specifically, as shown by adotted line in FIG. 16, on the first principal surface 1 a of the basemember 1, the spread suppressing member 3 may be provided with thedecoration layer 2, the adhesive layer 7, the metal layer 6, and thecarrier film 5 interposed therebetween.

In order to maintain the decorating effect of the pattern area 2 a ofthe decoration layer 2, as shown in FIG. 17, the thickness T₁ of theportion of the sheet 10 corresponding to the pattern area 2 a ispreferably in the range of about 1.1 times to about 1.8 times greaterthan the thickness T₂ of the other portion of the sheet 10. Morepreferably, the thickness T₁ is in the range of about 1.2 times to about1.6 times greater than the thickness T₂. When the pattern area 2 a has athickness T₁ less than about 1.1 times the thickness T₂, stepped cutsmay occur in the pattern area 2 a due to the unevenness of the surfaceof the molded article body 21, and desired decorating effects are notachieved. When the thickness T₁ is greater than about 1.8 times thethickness T₂, the appearance of the pattern area 2 a may be distorteddue to the lens effect, or the portion corresponding to the pattern area2 a (the portion is raised as compared with the other portion) may getscratched by friction.

In this preferred embodiment, the molded article body 21 which isintegrally formed (in other words, which has a single member) is shown.Alternatively, a molded article may have a plurality of members whichare separately molded, and the plurality of members may be mutuallycoupled by the decorative sheet 10.

Specifically, as shown in FIG. 18( a), on a surface of a molded articlebody 22 having a first member 22 a and a second member 22 b disposed ona surface of the first member 22 a, the decorative sheet 10 is joined soas to cover both of the first member 22 a and the second member 22 b. Asa result, as shown in FIG. 18( b), a molded article 20′ in which thefirst member 22 a and the second member 22 b are coupled is obtained.

A relative positional relationship between the first member 22 a and thesecond member 22 b can be arbitrarily selected. For this reason, whenthe plurality of members 22 a and 22 b of the molded article body 22 arecoupled by the decorative sheet 10, as described above, a large varietyof shapes of molded articles can be obtained by using a relatively smallnumber of molding dies. Therefore, the production of a large variety ofshapes of molded articles is easily performed at a low cost. For thefirst member 22 a and the second member 22 b, a structure fortemporarily tacking them, that is, a positioning structure fordetermining the relative positional relationship may be provided. Thepositioning structure may be a protruding portion and a concave portionwhich are mutually engaged, for example.

The molded article produced by the production method using thedecorative sheet 10 is suitably used for the interior or exterior ofmotor vehicles, exterior of home electric appliances, and many othersuitable molded articles. For example, the molded article is suitablyused as a tank cover 51, a front fender 52, and a tail cowl 53 of amotorbike 50 shown in FIG. 19. As is well known, a “motor vehicle”includes any locomotive conveyance or machine for transportingpassengers or merchandise, or for moving things, and includes a car, amotorcycle, a bus, a truck, a tractor, an airplane, a motorboat, a civilengineering vehicle, and many other motor vehicles. The motor vehiclesinclude not only those provided with an internal combustion engine, suchas a gasoline engine, but also those provided with an electric motor.

According to preferred embodiments of the decorative sheet of thepresent invention, since the spread suppressing member for suppressingthe spreading of the pattern area is provided in a locationcorresponding to the pattern area of the decoration layer, the spreadingof the pattern area when joined to the molded article body issuppressed. Accordingly, the decorative sheet according to preferredembodiments of the present invention is preferably used for thedecorating molded articles which have an uneven surface. When theproduction of the molded article is performed using the decorative sheetaccording to preferred embodiments of the present invention, distortionof the pattern is prevented, and the appearance of the obtained moldedarticle is greatly improved.

The molded article which is produced using the decorative sheetaccording to preferred embodiments of the present invention ispreferably used for various goods, and especially preferably used forthe interior and exterior of a motor vehicle.

The present invention is not limited to the above-described preferredembodiments, but can be modified in the scope of the attached claims.Further, the technologies disclosed in the above-described preferredembodiments can be used in combination, as desired.

1. A production method of a molded article comprising the steps of:preparing a decorative sheet including a base member formed from a resinmaterial, having first and second principal surfaces opposite to eachother, a decoration layer provided on the first principal surface of thebase member and having a pattern area representing a predeterminedpattern, and a member provided in a location corresponding to thepattern area and overlapping only a portion of, but not an entiresurface of, the first principal surface or the second principal surfaceof the base member and having a higher coefficient of thermalconductivity than a coefficient of thermal conductivity of the basemember; preparing a molded article body; heating the decorative sheet;and joining the decorative sheet which is heated to a surface of themolded article body in a condition in which a temperature of only aportion of the decorative sheet corresponding to the member is less thana temperature of another portion of the decorative sheet; wherein themember is provided on a side of the second principal surface of the basemember.
 2. The production method of a molded article of claim 1, whereinthe step of joining the decorative sheet to the surface of the moldedarticle body includes the step of cooling the decorative sheet such thatthe temperature of the portion corresponding to the member is rapidlyreduced as compared to the temperature of the other portion.
 3. Theproduction method of a molded article of claim 1, wherein the member isformed from a material including one of a metal and a metal compound. 4.The production method of a molded article of claim 1, wherein the memberis formed of metal.
 5. The production method of a molded article ofclaim 1, wherein a coefficient of thermal conductivity of the member isat least about 10 W/m·K.
 6. The production method of a molded article ofclaim 1, wherein a thickness of the member is in a range of about 5 μmto about 100 μm.
 7. The production method of a molded article of claim1, wherein the member includes a first portion which overlaps thepattern area and a second portion arranged along an outer circumferenceof the first portion.
 8. The production method of a molded article ofclaim 7, wherein a width of the second portion of the member is in arange of about 1 mm to about 10 mm.
 9. The production method of a moldedarticle of claim 7, wherein a width of the second portion of the memberis in a range of about 2 mm to about 8 mm.
 10. The production method ofa molded article of claim 1, wherein the step of joining the decorativesheet to the surface of the molded article body includes the step ofmoving the heated decorative sheet closer to the molded article body,and the step of reducing a pressure of a first space formed between thedecorative sheet moving closer to the molded article body and the moldedarticle body as compared with a pressure of a second space expandedoppositely to the first space with respect to the decorative sheet. 11.The production method of a molded article of claim 10, wherein the stepof moving the decorative sheet closer to the molded article body isperformed such that the member faces the second space.
 12. Theproduction method of a molded article of claim 11, further comprising,after the step of moving the decorative sheet closer to the molded body,the step of cooling the member by introducing a gas into the secondspace.
 13. The production method of a molded article of claim 11,further comprising, after the step of joining the decorative sheet tothe surface of the molded body, the step of removing the member.
 14. Theproduction method of a molded article of claim 1, wherein, after thestep of joining the decorative sheet to the surface of the moldedarticle body, the decoration layer is located between the base memberand the molded article body.
 15. The production method of a moldedarticle of claim 1, wherein the molded article body includes a firstmember and a second member disposed on a surface of the first member,and in the step of joining the decorative sheet to the surface of themolded article body, the decorative sheet is joined to the surface ofthe molded article body so as to cover both of the first member and thesecond member, thereby joining the first member and the second member.16. The production method of a molded article of claim 1, wherein thestep of heating the decorative sheet includes heating substantially anentire surface of the decorative sheet.
 17. A production method of amolded article comprising the steps of: preparing a decorative sheetincluding a base member formed from a resin material, having first andsecond principal surfaces opposite to each other, a decoration layerprovided on the first principal surface of the base member and having apattern area representing a predetermined pattern, and a member providedin a location corresponding to the pattern area and overlapping only aportion of, but not an entire surface of, the first principal surface orthe second principal surface of the base member and having a highercoefficient of thermal conductivity than a coefficient of thermalconductivity of the base member; preparing a molded article body;heating the decorative sheet; joining the decorative sheet which isheated to a surface of the molded article body in a condition in which atemperature of only a portion of the decorative sheet corresponding tothe member is less than a temperature of another portion of thedecorative sheet; and after the step of joining the decorative sheet tothe surface of the molded body, removing the member.